1. Field of the Invention
The present invention relates to a biocompatible and biodegradable elastomer, and, particularly, a biocompatibe and biodegradable elastomer suitable for the use of vascular graft.
2. The Prior Arts
Vascular graft can serve as vascular transplant material and substitute specific blood vessel in human body that is damaged by aging or pathologies such as atherosclerosis; or serve as graft fistula for patients undergoing hemodialysis. Vascular transplant materials often used in general surgical operations can be biological vascular graft or synthetic vascular graft.
Biological vascular graft includes autologous transplantation grafts and allogenic transplantation grafts, in which autologous transplantation grafts are often originated from saphenous veins or internal mammary arteries. Although saphenous veins and internal mammary arteries are ideal material, the source is limited. Allogenic transplantation grafts, on the other hand are usually the chemically treated blood vessels taken from animal bodies. Although the source of allogenic transplantation graft is much abundant, thrombus, vascular tangles, and aneurysm are likely to occur upon transplanting into human bodies.
The development of synthesized vascular graft dated from the success of vinyl chloride-acrylonitrile copolymer fiber (Vinyon N) vascular graft introduced by Voorhees in 1952. It was also been proofed to be clinically applicable. Synthesized vascular graft can also be categorized into non-biodegradable or biodegradable vascular graft according to its material. With respect to biological vascular graft, synthesized vascular graft is unlikely to cause problems such as immune response, thrombus, or vascular calcification, thus is considered to be the more ideal vascular graft for transplantation.
Biomedical materials for the applications of vascular graft preparation should take into account of factors such as good biocompatibility, outstanding flexibility and compliance, appropriate pore size, and having functional endothelial layer. Vascular graft, according to the diameter, can be divided into large diameter (>8 mm) vascular graft, medium diameter (6 to 8 mm) vascular graft, and small diameter (<6 mm) vascular graft (or namely small vascular graft). Small vascular grafts with diameter less than 6 mm can be used to substitute blood vessels with lower blood flow such as arteriole, coronary artery, or groin artery, however, currently the replacement of arteriole or vein with small vascular graft yet to reach satisfactory results due to undesirable long-term patency, as well as problems such as inner layer thickening of angiogensis and vascular narrowing or blocking. Hence, the development of small vascular grafts that possess similar characteristics to human artery and vein as well as good biocompatibility to minimize problems of inner layer thickening of the newborn vessel is a critical task for modern vascular graft engineering.
Biodegradable elastomer is the macromolecule that exhibits advantages such as elasticity and biodegradability as well as good biocompatibility, mechanical property, and workability, and can be widely used in the field of biomedicine, for example, hard tissue embedding, repairing material, surgical suture, carrier for drug release, and vascular tissue engineering. Thus, the development of a biocompatible and biodegradable elastomer with features that can be used as vascular graft can dramatically promote the advance of vascular tissue engineering.